The United Nations defines as refugee as someone who was forced to leave their country "owing to a well-founded fear of being persecuted for reasons of race, religion, nationality, membership in a particular social group, or political opinion, is outside the country of his nationality, and is unable to or, owing to such fear, is unwilling to avail himself of the protection of that country."
Under the 1951 Convention on Refugees and 1967 Protocol, a nation must grant asylum to refugees and cannot forcibly return a refugee to their nation of origin. Refugees are also the subject of the United Nations High Commissioner for Refugees (UNHCR). Many nations routinely ignore this treaty.
The United Nations created a second definition of the term "refugee" in regards to Palestinian Arabs, and Palestinian Arabs alone. For this group only, an Arab is officially considered a Palestinian refugee even if that person had recently immigrated to the British mandate of Palestine in the last two years before 1948.
Israeli and Jewish groups hold that it is unfair to have a unique definition of refugee for Palestinians that effectively allows all recent Arab immigrants to have the same rights as indigenous peoples of the area. There is a separate article on Jewish refugees.
See also: boat people[?]
Critique of second definition of refugee (http://www.netanyahu.org/brieffacabor)